Compressor system



J 7- c. s. BAKER COMPRESSOR SYSTEM Filed June 27, 1944 INVENTOR (720N125 JLBaRez'. BY

HIS ATTORNEY.

Patented June 24, 1947 COMPRESSOR SYSTEM Charles S. Baker, Corning, N. Y., assignor to Ingersoll-Rand Company, New York, N. Y., a

corporation of New Jersey Application June 27, 1944, Serial No. 542,286

4 Claims. (Cl. 2302.6)

This invention relates to compressor system and regulating apparatus therefor, and more particularly to apparatus forunloading such systems so that the compressor may start without pumping or compressing air or othercompressible fluid.

It' is common to provide regulators for compressors by means of which they are unloaded or loaded in accordance with pressure conditions, as well as conditions of speed. However, under unexpected conditions, such as current failure in the case of electrically driven compressors, stoppage of' the machine often occurs without unloading of the compressor, so that restarting under load causes damage to the motor.

It is accordingly an object of the invention to provide a system adapted to operate in the usual manner with pressure operated unloading apparatus, with the addition of means for condi tioning the unloading apparatus to permit unloading upon emergency stoppages, and to delay reloading thereafter.

A further object of the invention is to provide a system of that type for use in multi-stage compressors.

Further objects and advantages of the invention will be in part obvious and in part pointed out hereinafter.

;Inthe drawing inwhich is illustrated a preferred embodiment of the invention and in which similar parts are indicated by similar reference characters, there are included,

Figure 1, a side view partly in vertical section and partly diagrammatic, of a compressor system, including the regulating apparatus,

Figure 2, a vertical sectional view of a control valve for operating the compressorunloader,

Figure 3, a vertical sectional view of a pressure relief valve for the intercooler, and,

Figure 4, a vertical section through a portion of the high pressure cylinder and its unloader.

Referring to the drawing, the compressor of the system includes a compressor A, having in this instance a mir or low pressure cylinders |0, discharging to an intercooler B, a high pressure cylinder and a discharge receiver C. The low pressure-cylinders ID are provided with an intake manifold l2 havingan unloading valve D, which isadapted to close the intake for unloading the low pressure cylinders. A discharge manifold |3 isprovidedffor thelow pressure cylinders in to conductthepressure fluid to the intercooler B, there being a high pressure inlet pipe M for connecting thev outlet side of the intercooler Bto the intake of the high pressure cylinder A suitable conduit |5 conducts the pressure fluid from the discharge of the high pressure cylinder to the receiver C. The fluid passing through the unloader valve D may be cleansed by a filter E of any well-known type.

The unloader valve D is of a well-known construction, and comprises a balanced moving valve element l6 reciprocable in double ported passage I! and held biased to its open position by a suitable spring |8. The valve I6 is adapted to be closed by a piston I9, operable by pressure fluid from the receiver 0. For this purpose, a pressure controlled valve F is provided, which may be of a well-known type, such as is shown in Castle and Rogers U. S. Patent No. 1,138,278, of May 4, 1915. This valve is adapted to operate at some predetermined high pressure to supply fluid under pressure to a conduit 20 leading to the piston chamber 2|, for actuating the piston I9. At a predetermined low pressure, valve F operates to exhaust the line 20 and piston chamber 2|, permitting the piston H! to return to its normal unactuated position.

Upon closing of the intake of the low pressure cylinders II] by the unloader D the intercooler B and its associated manifold l3 and conduit M are adapted to be exhausted of pressure fluid remainingtherein, by means of a pressure relief valve G shown in detail in Figure 3. Details of the intercooler Bare not shown. It may be of the well-known radiator type, but regardless of its construction, there is inherently a pressure drop from its inlet to its outlet as long as fluid is passing through it. This pressure drop is used to control the operation of the pressure relief valve G. i

To this end, the valve G is provided with a body portion 25, adapted to be screwed in to the intercooler B at a point preferably adjacent the intake of the intercooler. The body portion 25 has a flange 26 which cooperates withthe flange 21 of a cover portion 28 to house a diaphragm 29, separating the interior space between the cover 28 and the body portion 25 into two chambers 3|] and 3|. The chamber 33 is connected with the conduit M by a pipe 32, there being a tapped aperture 33 provided in the cover 28, as well as a restricted orifice 34 preventing sudden changes of pressure in the chamber 30.

The chamber 3| on the opposite side of the diaphragm 29 communicates with the interior of the intercooler B by way of a bore 35'provided with a relatively small orifice 36, which, also, is designed to prevent sudden changes in pressure within the chamber 3|. The purpose of the diaphragm 29 is to actuate a pressure relief valve 31 slidably mounted in sleeve 38, contained in a bore 39, longitudinally disposed in the body 25. The inner end of the sleeve 38 forms a seat for the head of the valve 31. The valve 3'! is adapted to control the flow of pressure fluid from the interior of the intercooler B to atmosphere and to this end a bore 40 is provided in the body 25 extending to a point adjacent the head of the valve 31 and registering with a port H in the sleeve 38.

The valve 31 is necked as at 42 to permit the passage of fluid within the interior of the sleeve 3'! to the bore 38 when the head of the valve is off its seat. A vent 43 to atmosphere leads from the bore 39 to the exterior of the body portion 25 and is tapped to permit the connection to a pipe 4 5. When air is the medium being pumped by the compressor it is not particularly important where this pipe may lead to. In the case of other gases it should be hooked up to the source of the gas. Therefore, this pipe is threaded into the system at the wall of the unloader valve D as shown at 45. Valve 3? is adapted to move with the diaphragm 29 in either direction and to this end it is attached to a plate 26 which is in turn bolted fast to the diaphragm, there being a corresponding plate 41 provided On the opposite side of the diaphragm so that the diaphragm is clamped between the plates 48 and 41, a ring of screws 48 passing through the diaphragm being provided for this purpose.

The second stage, or high pressure cylinder is provided with an unloader H which acts automatically upon reduction of the pressure in the intake 49. The unloader is adapted to operate upon the discharge plate valve 58 to hold that valve off its seat 5|. As shown in Figure 4, the intake valve assembly comprising the stop plate 52, valve plate 58, and seat 5!, are held in place in the cylinder wall 53 by means of a perforated cage 54, held in position by a jack screw 55 in the cover plate 56, suitably bolted and gasketed in the head of the high pressure cylinder H.

The cage 58 forms a cylindrical'guide for a combination valve and valve lifter 51 having fingers 58 arranged to contact the valve 58 to hold it off its seat. The upper portion of the valve lifter 5'! is cylindrical. as shown at 59, and is slidable in the cage 54. The valve lifter 5'! has a conical seat 68 cooperating with a corresponding seat 6! in the cage 54 to control the flow of pressure fluid from the intake 49 to the interior of the lifter 51 and the cage 54, which is vented to atmosphere by means of an aperture 63 in the cage E l, registering with a hollow jack screw 55. Normally, the lifter 5'! is held against its seat by the pressure of the fluid within the intake 49. When this pressure is relieved, however, the lifter 5! is pushed from its seat and to its valve lifting position by a spring 64 disposed within the lifter 51 and bearing at one end against the interior of the cage 54. In the valve lifting position, venting is provided through an aperture 85 passing through the cylindrical wall 58 of the valve lifter 51?. For reasons explained above, venting may be provided to the inlet of the compressor at the threaded aperture 6'! of the unloader D by means of a pipe 68 connecting this aperture with the end of the hollow jack screw 55.

Normally, the operations of the unloader D and H are controlled by the pressure operated Valves F and G, respectively. That is to say, upon operation of the valve F the unloader D operates to shut off the intake to the first stage cylinders III, which almost immediately causes cessation of the flow of pressure fluid through the intercooler B. Thereupon, the valve G operates because of the unbalance on the diaphragm 29 to vent the intercooler and its exhaust manifold l3 and conduit I4. It will be noted that the unbalance on the diaphragm 29 is due to the slight difference in areas of the opposite sides of the diaphragm, and is the pressure on the area of the valve stem 31. This causes the pressure to drop in the high pressure cylinder intake 49,

whereupon the valve lifter 5'! unseats the valve 50 and opens the atmospheric vent through the hole 65. It may be explained that the vent through the hole insures venting even though valve 37 has returned to its seat for want of actuating pressure within the intercooler B and associated parts.

It is understood, of course, that further appa ratus of well-known character may be provided to shut down the compressor upon its unloading in the manner described, and to automatically start it up. Such apparatus is not described here as it is no part of this invention. It will be noted, however, that, due to the currentv failure or other cause, the compressor may stop momentarily without unloading. In that case, if thecurrent should return to the line to start the compressor while loaded, extremely high current flow will ocour, and because of the acceleration under load damage may result.

This invention provides meansv to prevent the compressor system from remaining loaded when the compressor stops. For this. purpose, a. pressure operated control valve K is provided which is controlled by the pressure in the. intake manifold l2 of the compressor and by the pressure within the intercooler B. The controller K comprises in this instance, a valve 10, and its seat H housed within a valve body 12, attached to and forming a closure for the piston chamber 21 of the unloader D. The valve 10 is adapted to control flow of motive fluid from. the receiver C through a pipe 13 to the piston chamber 2|. The valve 10 is also adapted to control the flow and exhaust of motive fluid from the chamber 2| to the pipe 28. To accomplish this, the valve 10 is adapted to seat as at 14 at the end of a passageway in the hollow plug 15, set into the valve body 12, to which the pipe 20 is attached. Access to the piston chamber 2| is provided by a passageway [6.

Normally, valve 18 is held off its seat 14 and upon seat H by a relatively strong spring 11, capable of overcoming the air pressure against the valve in the opposite direction. To unseat the valve 18 there is provided a diaphragm 80 between flange 8| of the val-ve body l2, and a cupshaped portion 82 bolted to the flange 81. There are thus provided a lower chamber 83 and an upper chamber 84. The lower chamber 83 is constantly under pressure of the intercooler B, there being an interconnecting conduit 85. Chamber 84 is normally exposed to the same pressure that prevails in the intake manifold [2. For this purpose, a pipe 86 connects the intake manifold with the chamber 84. As shown in Fig. 2 the cup-shaped portion 82 is provided with a check valve, consisting of a plug 8.1, screwed into the wall of the cup 82, and bored to receive the ball valve 88 seating at the end of a counter bore 89. A strong spring 90 is provided between the valve 88 and a plug 9| to hold the valve 88 on its seat.

Diaphragm 80 is adapted to unseat the valve 88 by means of a plunger 92 extending through the counter bore 89 and attached to the diaphragm by means of a stud 93. Motion of the diaphragm 80 in the opposite direction is adapted to unseat the valve by pressure against a plunger 94 extending through and closely fitting a bore 95 in body 72. There is a normal tendency of the diaphragm to a position unseating the valve 79 due to the pressure of a spring 98, preferably mounted about the Plunger 92 and bearing against the plug 87.

If we assume that the compressor has stopped due to some abnormal cause, while fully loaded as above described, it will be noted that the intercooler will vent itself by the action of the valve G as above described, and that the high pressure cylinder II will also unload due to the action of the unloader H. This action will immediately relieve the pressure in the chamber 83, causing the diaphragm 80 to lift the valve 10 from its seat H and to shut off communication between the chamber 2| and pipe 20, which would under such conditions, be an exhaust to atmosphere through the valve F. This action will permit motive fluid to enter the piston chamber 2| by way of the pipe 13 immediately closing the intake unloader D. Thus, when the compressor restarts, it is unloaded but it would tend to remain so indefinitely, because the compressor is incapable of supplying any air to build up pressure in the intercooler. This condition is counteracted by providing a slow leak from the chamber 84 by way of a small orifice in a plug 96 which is connected by a bypass pipe 91 to the pipe 86. Due to the fact that the compressor is drawing a vacuum in the intake manifold 12 a gradual reduction of pressure takes place in the chamber 84 by way of the bypass pipe 97. Slowly, therefore, the diaphragm 89 rises to seat the valve 10 on its seat H, and to permit the unloader D to pass air to the compressor manifold I2. Likewise, the ball valve 88 is unseated by the plunger 92. Upon operation of the unloader D the motive fluid begins to flow through the intercooler B at a rapid rate causing the valve G to stop the vent ing of the intercooler. The flow of the fluid into the high pressure cylinder intake 49 becomes relatively rapid so that it cannot escape by way of the hole 65 and the valve lifter 57, and as pressure builds up, the valve lifter overcomes the compression of the spring 64 to lift the valve lifter and permit the intake valve 50 to operate normally. The compressor is then fully loaded and should remain so and during its normal conditions the pressure valve F assumes control of the loading and unloading.

I claim:

1. A compressor system including first and secand stage compression cylinders, an intercooler interposed therebetween, a discharge receiver for the second stage cylinder, 2. pressure operated unloader for the first stage cylinder, means to operate the first stage unloader upon reaching a predetermined maximum discharge pressure in the receiver, and means acting independently of the first said means and in response to the pressure in the intercooler to operate said first stage unloader at the end of each period of operation of the compressor.

2. A compressor system including first and second stage compression cylinders, an intercooler interposed therebetween, a discharge receiver for the second stage cylinder, a pressure operated unloader for the first stage cylinder, means to operate the first stage unloader upon reaching a predetermined maximum discharge pressure in the receiver, and means acting independently of the first said means to operate said first stage unloader at the end of each period of operation of the compressor, including a valve jointly controlled by the intercooler pressure and the pressure of the first stage intake to introduce and exhaust pressure fluid to and from the first stage unloader.

3. A compressor system including first and second stage compression cylinders, an intercooler interposed therebetween, a discharge receiver for the second stage cylinder, a pressure operated unloader for the first stage cylinder, means to operate the first stage unloader upon reaching a predetermined maximum discharge pressure in the receiver, and pressure responsive means acting independently of the first said means to operate said first stage unloader at the end of an operating period of the compressor, including a valve to control the flow of pressure fluid to and from the first stage unloader, a diaphragm for actuating said valve, an exhaust on opposite sides of the diaphragm to the intercooler and the intake of the first stage cylinder, and means to restrict the reductionof pressure at one side of the diaphragm when the intercooler pressure is reduced to atmosphere.

4. Regulating apparatus for a pressure fluid compressor for high and low pressure cylinders, an intercooler and a receiver comprising a pressure fluid actuated unloader for the low pressure cylinder, an unloader for the high pressure cylinder, a pressure relief valve for the intercooler,

' and means to control the operation of said unloader, including a valve controlling the flow of pressure fluid to the low pressure cylinder unloader and an actuating member 'for the valve exposed to pressure of the intercooler to permit closing of said valve and oppositely influenced by the pressure in the low pressure cylinder intake.

CHARLES S. BAKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,137,752 Ferguson Nov. 22, 1938 2,221,789 Ferguson Nov. 19, 1940 1,607,531 Haight Nov. 16, 1926 1,881,092 Noble Oct. 4, 1932 

